A. Field of the Invention
The present invention relates generally to the communications field, and, more particularly to a fiber optic cable management system.
B. Description of the Related Art
Presently, it is a problem in the field of communication cable installation to ensure the precise placement of the communication cable without the possibility of damage to the communication cable by the provision of tight bends, or inappropriate use of fasteners, or inadequate support to the communication cable. Such communication cables include conventional telephone cable having a plurality of copper conductors, coaxial cable, optical fiber, or the like. In all of these applications, the minimum radius of curvature of the communication cable is well defined, and bending the communication cable in a tighter bend can cause damage to the communication medium housed within the cable. The installer of communication cable is thus faced with the problem of routing the communication cable over surfaces, which typically include sharp bends, without over bending the communication cable, yet also securing the communication cable to these surfaces in a manner to ensure protection from damage.
This problem is further heightened when fiber optic cables (alternatively referred to as “optical fibers” or “fibers”) are used. Glass fibers used in such cables are easily damaged when bent too sharply and require a minimum bend radius to operate within required performance specifications. The minimum bend radius of a fiber optic cable depends upon a variety of factors, including the signal handled by the fiber optic cable, the style of the fiber optic cable, and equipment to which the fiber optic cable is connected. For example, some fiber optic cables used for internal routing have a minimum bend radius of 0.75 inches, and some fiber optic cables used for external routing have a minimum bend radius of 1.0 inches.
Damaged fiber optic cables may lead to a reduction in the signal transmission quality of the cables. Accordingly, fiber optic cables are evaluated to determine their minimum bend radius. As long as a fiber optic cable is bent at a radius that is equal to or greater than the minimum bend radius, there should be no reduction in the transmission quality of the cable. If a fiber optic cable is bent at a radius below the minimum bend radius determined for such cable, there is a potential for a reduction in signal transmission quality through the bend. The greater a fiber optic cable is bent below its minimum bend radius, the greater the potential for breaking the fiber(s) contained in the cable, and the shorter the life span of the cable.
Optical communication equipment is typically housed in bays, which include a rectangular frame having dimensions conforming to a particular standard, such as the Network Equipment Building Standard (NEBS). NEBS was originally developed by Bell Telephone Laboratories in the 1970s and expanded by Bellcore. Long a requirement for equipment used in the Central Office in the North American Public Switched Network, the NEBS criteria have become a universal measure of network product excellence.
NEBS covers a large range of requirements including criteria for personnel safety, protection of property, and operational continuity. NEBS covers both physical requirements including: space planning, temperature, humidity, fire, earthquake, vibration, transportation, acoustical, air quality and illumination; and electrical criteria including: electrostatic discharge (ESD), electromagnetic interference (EMI), lightning and AC power fault, steady state power induction, corrosion, DC potential difference, electrical safety and bonding and grounding. The term “electrostatic discharge” or “ESD”, as used herein, refers to the rapid, spontaneous transfer of electrostatic charge induced by a high electrostatic field. Usually the charge flows through a spark (static discharge) between two bodies at different electrostatic potentials as they approach one another.
An optical communications equipment frame further typically has a plurality of shelves, each having one or more slots for accommodating circuit boards or cards that have optical and electrical components associated with a communication network mounted thereon. The components include, but are not necessarily limited to lasers, photodetectors, optical amplifiers, switching elements, add/drop multiplexers etc. In addition, fiber optic cables typically connect to one or more component.
If a network component requires maintenance or an upgrade, the card containing the component or a component module is typically removed from the shelf. However, since fiber optic cables are typically fragile, if the fiber optic cable is bent beyond the minimum bend radius during board or module removal, the fiber optic cable may break. Accordingly, removal and insertion of component boards or modules can be difficult and inconvenient.
Furthermore, the recent increase in bandwidth requirements for telecommunications systems has resulted in more densely packed equipment and fiber optic cables than prior systems. Many carriers or other consumers of optical communications equipment have a very limited floor space in which to place new equipment and fiber optic cables. For example, some carriers may only have a single open bay (or shelf) in which to place new equipment and fiber optic cables. If the communications equipment can be more densely packed, then a greater amount of equipment and fiber optic cables may be placed within the available space. The fiber optic cables housed within optical communications equipment is also exposed to damage when the doors to the equipment are closed due to the close fit between the doors and the fiber optic cables.
Thus, it is even more necessary now to be able to bend fiber optic cables around corners and other obstacles in order to route the cables to and from equipment such as computers, connector panels, junction boxes, etc. In some conventional systems, standard plastic parts route the fiber optic cables. These plastic parts are often too large and generic to work in the new, denser systems. In other conventional systems, custom sheet metal parts route the fiber optic cables. Custom sheet metal is expensive and also cannot be used in the new, denser optical communications systems, since they can cause damage to the densely-packed fiber optic cables in such systems.
Thus, there is a need in the art to provide an inexpensive means for routing fiber optic cables in the new, denser optical communications systems that may be easily customized by an installer and prevent the fiber optic cables from being bent beyond their minimum bend radii.